With the ever-increasing demand for wireless transmission capacity, be it the number of users able to access a system or the speed at which data is transferred, multiple input multiple output (MIMO) architectures have evolved. MIMO architectures incorporate multiple antennas for transmission and multiple receivers for reception. In combination with various coding techniques, the spatial diversity provided by MIMO systems provides for significant increases in the number of users that can access a system at any given time, as well as the amount of data that can be transmitted over a given period of time. Unfortunately, the nature of mobile communications dictates the need for inexpensive mobile terminals, such as mobile telephones, wireless personal digital assistants (PDAs), and the like. Implementing a mobile terminal having multiple antennas significantly increases its complexity, and thus its price. To date, the price associated with providing multiple antennas and transmission paths in mobile terminals has significantly outweighed the benefit of more capacity, at least from the consumer's perspective.
Most base stations are already equipped with multiple antennas and receivers, and given the nature of such an infrastructure, the cost of providing such has proven largely insignificant. Thus, there exists a wireless infrastructure capable of facilitating MIMO-based communication, yet consumers are unwilling to bear the cost of completing the MIMO environment by buying properly equipped mobile terminals. As such, there is a need to reap the benefit of MIMO-based communications without requiring mobile terminals to have multiple antennas.
In order to accommodate this need, virtual MIMO systems have emerged. An exemplary virtual MIMO system is disclosed in commonly owned and assigned U.S. Patent Application Publication No. 2004/0114618, entitled VIRTUAL MIMO COMMUNICATION SYSTEM, filed Dec. 16, 2002, which is hereby incorporated by reference in its entirety. In general, a virtual MIMO system is created by pairing mobile terminals. However, virtual MIMO systems require a scheduler for pairing mobile terminals. Thus, there remains a need for a scheduler for a virtual MIMO system.